Distal Radioulnar Joint Subluxation

The radius and ulna constitute a bicondylar joint, articulating at distal and proximal radioulnar joints. Between these two joints, the interosseous membrane functions as a suspension bridge. The stability of proximal and distal radioulnar joints is provided by the thick and complex ligamentous structures, known as the annular ligament and the triangular fibrocartilage complex, respectively. The distal radioulnar joint consists of two articular surfaces that are dissimilar in their radius and curvature, the sigmoid notch and the ulnar seat. MRI is useful to evaluate for TFCC injury and to assess DRUJ subluxation.  Note the positive ulnar variance and widening of the DRUJ space is this case.